This is a longitudinal study of the combined effects of iodide deficiency and protein deficiency on intellectual, neurological and physical development in a region where endemic goiter is highly prevalent. Iodized oil is administered in controlled mode to chosen members of the population group. The effects of this on goiter and on growth and development of children are measured. In addition, lysine-typtophane supplements are given to the predominantly maize diet in a controlled model in order to assess the effect of this improvement in protein availability on neurological and physical growth and development. These supplements are given during pregnancy, and the children of these pregnancies are followed for their growth and development. A total of approximately 3500 persons are involved in the overall study.